Tuesday 7 August 2012 06.45 EDT
First published on Tuesday 7 August 2012 06.45 EDT

Two days after regaining consciousness from a massive stroke, Richard Marsh watched helplessly from his hospital bed as doctors asked his wife, Lili, whether they should turn off his life support machine.

Marsh, a former police officer and teacher, had strong views on that suggestion. The 60-year-old didn't want to die. He wanted the ventilator to stay on. He was determined to walk out of the intensive care unit and he wanted everyone to know it.

But Marsh couldn't tell anyone that. The medics believed he was in a persistent vegetative state, devoid of mental consciousness or physical feeling.

Nothing could have been further from the truth. Marsh was aware, alert and fully able to feel every touch to his body.

"I had full cognitive and physical awareness," he said. "But an almost complete paralysis of nearly all the voluntary muscles in my body."

The first sign that Marsh was recovering was with twitching in his fingers which spread through his hand and arm. He describes the feeling of accomplishment at being able to scratch his own nose again. But it's still a mystery as to why he recovered when the vast majority of locked-in syndrome victims do not.

"They don't know why I recovered because they don't know why I had locked-in in the first place or what really to do about it. Lots of the doctors and medical experts I saw didn't even know what locked-in was. If they did know anything, it was usually because they'd had a paragraph about it during their medical training. No one really knew anything."

Marsh has never spoken publicly about his experience before. But in an exclusive interview with the Guardian, he gave a rare and detailed insight into what it is like to be "locked in".

"All I could do when I woke up in ICU was blink my eyes," he remembered. "I was on life support with a breathing machine, with tubes and wires on every part of my body, and a breathing tube down my throat. I was in a severe locked in-state for some time. Things looked pretty dire.

"My brain protected me – it didn't let me grasp the seriousness of the situation. It's weird but I can remember never feeling scared. I knew my cognitive abilities were 100%. I could think and hear and listen to people but couldn't speak or move. The doctors would just stand at the foot of the bed and just talk like I wasn't in the room. I just wanted to holler: 'Hey people, I'm still here!' But there was no way to let anyone know."

Locked-in syndrome affects around 1% of people who have as stroke. It is a condition for which there is no treatment or cure, and it is extremely rare for patients to recover any significant motor functions. About 90% die within four months of its onset.

Marsh had his stroke on 20 May 2009. Astonishingly, four months and nine days later, he walked out of his long-term care facility. Today, he has recovered 95% of his functionality; he goes to the gym every day, cooks meals for his family and last month, he bought a bicycle, which he rides around Napa Valley, California, where he lives.

But he still weeps when he remembers watching his wife tell the doctors that they couldn't turn off his life support machine.

"The doctors had just finished telling Lili that I had a 2% chance of survival and if I should survive I would be a vegetable," he said. "I could hear the conversation and in my mind I was screaming 'No!'"

Locked-in syndrome is less unknown than it once was. The success of the 2007 film, The Diving Bell and the Butterfly, the autobiography of the former editor of French Elle magazine editor, Jean-Dominique Bauby, brought awareness of the condition to the general public for the first time.

Then in June, Tony Nicklinson challenged the law on assisted dying in England and Wales at the High Court as part of his battle to allow a doctor to end a life he said was "miserable, demeaning and undignified". Judgment was reserved until the Autumn.

Marsh, however, did something almost unheard of: he recovered. On the third day after his stroke, a doctor peered down at him and uttered the longed-for words: "You know, I think he might still be there. Let's see."

The moment that doctor discovered Marsh could communicate through blinking was one of profound relief for Marsh and his family – although his prognosis remained critical.

"You're at the mercy of other people to care for your every need and that's incredibly frustrating, but I never lost my alertness," he said. "I was completely aware of everything going on around me and to me right from the very start, unless when they had me medicated," he said.

"During the day, I was really lucky: I never spent a single day when my wife or one of my kids wasn't there. But once they left, it was lonely – not in the way of missing people but the loneliess of knowing there's no one there who really understands how to communicate with you."

The only way for Marsh to sleep, was to be medicated. That, however, only lasted four hours, after which there had to be a three-hour pause before the next dose could be administered.

In response to another question, about the right-to-die debate, Marsh said he has no opinion. All he will say is: "I understand the despair and how a person would reach that point." But he is co-writing a book that he hopes will inspire hope and provide information to victims of locked-in syndrome and their families.

"When they first told my family that I was probably locked-in, they tried to find information on the internet – but there wasn't any. One of my goals now is to change that … to be able to reach out to families who find themselves in the same situation that mine were in so they can help their loved ones.

"Time goes by so slow ... It just drags by. I don't know how to describe it. It's almost like it stands still.

"It's a terrible, terrible place to be but there's always hope," he added. "You've got to have hope."

• This article was amended on 10 August 2012. The original said that Tony Nicklinson had failed in his High court bid to change the law on assisted dying in England and Wales. This has been corrected.